Early morphogenesis of ciliated cells in human oral cavity

Ciliated cells were found in the epithelium of the oral cavity of human embryos and fetuses starting from the seventh week of prenatal development. At the early stages of prenatal development (until the 13th week), cells with cilia cover most of the dorsal surface of the tongue and the soft palate, whereas they are found only near the gland ducts in the circumvallate and foliate lingual papillae after 17 weeks of development. The ultrastructure of the axoneme of cilia corresponds to the structure of motile cilia and is represented by nine microtubule doublets that surround the central pair of microtubule singlets. An immunohistochemical study performed on weeks 10–12 of development identified nerve endings associated with the ciliated cells. Until the 14th week of development, the cytoplasm of ciliated cells is immunopositive for NSE. The spatial distribution of ciliated cells in the tongue epithelium until the 13th week of development is not related to the morphogenesis of lingual papillae, and their role in the human oral cavity during the first trimester of pregnancy is unclear and requires further study.     

"Light" epithelial cells of swine and bovine oviducts

The ultrastructure of oviduct epithelium of clinically healthy cows and 15 sows was investigated using scanning and transmission electron microscopy. In all parts of the oviduct, ciliated and non-ciliated epithelial cells are present, but their number varies in both the investigated animals in different regions of the oviduct, depending on the phase of the estrous cycle. In addition to ciliated cells with numerous cilia on their luminal surface, so-called pale ciliary cells were found in all parts of the oviduct of cows and sows. The cytoplasm of these cells is electron-lucent, their luminal surface carries few cilia and short microvilli. The apical cytoplasm contains species specific secretory granules, which means that these cells have features characteristic of both secretory and ciliated cells. It is suggested that the pale ciliated and non-ciliated secretory cells are functional stages of the same tubar epithelium cell, and that the transformation between these two cell types is regulated by functional requirements of the organ in different phases of the estrous cycle.     

花背蟾蜍(Bufo raddei Strauch)眼形态发生过程中角膜上皮表面结构的扫描电镜观察

扫描电镜观察表明,花背蟾蜍眼形态发生过程中角膜上皮细胞表面形态结构的变化,大致可分三个阶段。1.从神经管期至肌肉感应期预定角膜上皮表面无明显变化;2.在心跳期和鳃血循环期预定角膜上皮表面出现较多的细胞缢束和其下细胞表面的下陷;3.在以后各期,角膜上皮中纤毛细胞的纤毛逐渐退化消失,在右鳃盖封闭期纤毛细胞全部消失。上述变化与视网膜及其中光感受器的发育分化密切相关,纤毛的退化和消失更精确地反映了这种依赖关系,似可作为角??膜上皮分化的一个形态指标。     

Ultrastructural study of the ciliated cyst in the human uterine tube epithelium

Ciliated cysts in the human uterine tube epithelium were investigated with the transmission electron microscope. The cysts were about 3-9 microns in diameter and were provided with many ciliary apparatuses and microvilli. Degenerative changes of these cilia, such as electron-dense round or irregular bodies and amorphous substance, were observed in many cysts, but complete disappearance of ciliary structures was not detected in any ciliated cysts. The ciliated cysts were mostly observed in basal cells and were occasionally found in ciliated cells bordering the tubal lumen. In the basal cells, these cysts distended with the increase in degenerated cilia. Distended ciliated-cyst-containing cells became exposed directly to the tubal lumen. U- or reverse omega-shaped deep indentations of the apical surface of ciliated cells confirmed the opening of ciliated cysts into the lumen. It was suggested that the ciliated cysts result from the premature differentiation of basal cells or disturbed migration of centrioles in ciliogenic cells.     

Surface ultrastructure of the olfactory rosette of an air-breathing catfish,Heteropneustes fossilis (Bloch)

The surface architecture of the olfactory rosette ofHeteropneustes fossilis (Bloch) has been studied by scanning electron microscopy. The olfactory rosette is an oval structure composed of a number of lamellae arranged pinnately on a median raphe. The raphe is invested with epithelial cells and pits which represent goblet cell openings. On the basis of cellular characteristics and their distribution the lateral surface of each olfactory lamella is identified as sensory, ciliated non-sensory and non-ciliated non-sensory epithelium. The sensory epithelium is provided with receptor and supporting cells. The ciliated non-sensory epithelium is covered with dense cilia obscuring the presence of other cell types. The non-ciliated non-sensory epithelium is with many polygonal areas containing cells.     

Structure of the uterine luminal epithelium of the brush-tailed possum (Trichosurus vulpecula)

Morphology and morphometry of the luminal surface of the uterus of the brush-tailed possum were studied during the oestrous cycle, in anoestrous animals and after ovariectomy. At oestrus the secretory cells were small and the epithelium heavily ciliated. The relative surface area occupied by secretory cells reached a maximum on Day 13 when plasma progesterone concentrations are maximal. The mean apical surface area of the secretory cells also reached a maximum at this time. Both these measures decreased on Day 18 when involution of the epithelium was taking place. This process was essentially complete by Day 24 and was followed by extensive ciliogenesis. Secretory cells from anoestrous animals appeared to have an apical surface area similar to the minimum recorded during the oestrous cycle and extensive loss of cilia did not occur. Ovariectomy caused loss of ciliated cells and a reduction in the mean apical surface area to a dimension much smaller than that measured in intact animals.     

The inside surface of the rat esophagus during ontogenesis]

The surface architecture of rat esophagus during the ontogeny is studied. Single cilia on the cells of the apical surface can be observed with the scanning electron microscope till the day 17 of the fetal period. Ciliogenesis and function of the single cilia are discussed by literature. Based upon results of our investigations we give the following interpretation: The single cilia are responsible for differentiation of the transitional columnar epithelium. The stop of mitosis, which is connected to constitution of single cilia, allows the formation of cell organelles. About the day 21 after conception ciliary cells are found. Their function is still unknown. They are observed on the esophageal surface at the same time, when primary ciliary cells arise on the trachea of the rat. The columnar epithelial cells transform into a squamous epithelium within 48 hours. The keratinisation and exfoliation of the surface cells occur definitely post-partum.     

Scanning electron microscope study of the lung epithelium of the rabbit during ontogenesis

The development of the bronchial and alveolar epithelium was observed in rabbits from the 15th day post conception until the time of birth with the scanning electron microscope. In the pseudoglandular phase, primitive bronchi proliferate in the mesenchyme. The epithelial cells are not differentiated and have single cilia. After retraction of these single cilia cell differentiation begins. Flat cells densely populated with cytopodia can be recognized on the 22nd day, ciliated cells on the 23rd day post conception. Both are located in the bronchi near the hilus. In the canalicular phase of development, the differentiation of the mucoid cells and the Clara-cells begins. The interstitial connective tissue develops more and more capillaries. The alveolar phase begins around the 26th day p. c. The lung capillaries reach the alveolar epithelial cells and arrange themselves directly beneath the epithelial basement membrane. This "alveolarization" of the lung tissue starts in the centre of the lung lobules and proceeds to the periphery. After the 26th day post conception the alveolar epithelial cells retract their single cilium and at the same time become type I or type II pneumocytes. The undifferentiated entodermal stem cell of the alveolar epithelium is the pneumoblast.     

Light and electron microscopic observations on ciliated vacuoles and cysts in the oviductal and endocervical epithelia of the rabbit

Ciliated vacuoles and intraepithelial cysts have been observed in oviductal and endocervical epithelia of rabbits. In this study, rabbits under various hormonal conditions were studied by light and transmission electron microscopy and tissue culture in an attempt to determine their distribution and origin. Ciliated vacuoles most frequently lay in the basal cytoplasm, below or beside the nucleus, and very close to the basal lamina. A few were apically located. Their average diameter was 8.8 by 5.1 microns. Cilia and microvilli projected into the vacuolar lumen. These vacuoles were located intracellularly as evidenced first by the degeneration of both their cilia and microvilli and the moderately dense matrix that often filled the vacuolar lumen, as observed by electron microscopy. Secondly, phase microscopy of the living endocervical epithelium allowed us to observe the beating of the cilia within the vacuoles, not on the surface of such cells. Thirdly, ruthenium red stained the surface glycocalyx of ciliated and secretory cells, but not that of the cilia and microvilli within the vacuoles. The intraepithelial cysts were not observed in all tissue blocks. The largest numbers were found in ovariectomized animals treated for 3 and 5 days with estradiol. More were seen in the isthmus and cervix than in the fimbria and ampulla. The cysts were located most often within the epithelium along the sides of, and at the bases of, the mucosal folds. They were lined by flattened epithelium of various combinations of secretory and ciliated cells. An unusual cell type was associated with some of the cysts and ciliated vacuoles. Its cytoplasm contained aggregates of mitochondria and vesicles whose contents varied in density. Although the genesis of the ciliated vacuoles is not certain, our results indicate that they may arise from aberrant positioning of proliferating procentrioles or from a defect in targeting or transporting the centrioles to the apical plasma membrane to serve as basal bodies. Fusion of adjacent ciliated vacuoles with lumina lined by secretory cells having deep apical invaginations appeared to contribute to the formation of cysts.     

The histology and fine structure of the olfactory organ of the squid Lolliguncula brevis Blainville.

The olfactory organ of the squid has a thick, pseudostratified epithelium containing five morphological types of ciliated receptors. In the simplest receptors the cilia originate separately in the distal pole of the cell. All other receptors have some type of cilia filled cavity, varying from a simple pocket of cilia at the surface to a completely closed vesicle filled with cilia in cells deep in the epithelium. The receptors are compared to cells in the rhinophore of Nautilus and the olfactory organs of coleoid cephalopods. Possible functions of the olfactory organ, based on its morphology, are discussed.     

Single modified cilia displayed by cells of human internal stratified epithelia (oral cavity,vagina)

Summary Serial sections of human vaginal and keratinized oral-gingival epithelia were investigated for ciliary structures. Most melanocytes of the gingival epithelium lacked cilia, whereas almost all basal keratinocytes of the deeper portion of the epithelial ridges possessed one cilium each. In the suprabasal layers of the ridges only a few keratinocytes exhibited a single cilium. In the basal layer, at the top of the connective tissue papillae, approximately every second keratinocyte displayed a single cilium. In the suprabasal layers above the ridges no ciliated keratinocytes were observed. The basal cells of the vaginal epithelium were endowed with cilia, while cilia were absent from the suprabasal cells. In the human forearm epidermis most melanocytes and keratinocytes are supplied with a single cilium; it has been suggested that they may play a role in light reception. However, the widespread occurrence of 9 + 0 cilia in epithelial cells of internal epithelia and their coincidence with the sites of renewal of keratinocytes suggests that a relationship may exist between solitary cilia and mitotic activity.     

Stereoscan studies of eggs, free-swimming and penetrating miracidia and early sporocysts of Fasciola hepatica.

The egg of Fasciola hepatica has a smooth surface with a slightly elevated circle marking the fracture of the operculum. The operculum and the aperture have crenated edges. The epithelial cells of the miracidium are covered with long cilia. When miracidia are vibrated in an ultrasonic cleaner the cilia of the epithelial cells of the four posteroir tiers are broken off only leaving longitudinal rows of cilium stubs, whereas the cilia of the first tier are still retained. The apical papilla is provided with a dorso-ventral furrow, multiciliated pits and isolated sensory cilia. The narrow intercellular ridge is smooth, whereas the epithelial cells have small cytoplasmic knobs between the cilia. The penetration into the snail (Lymnaea truncatula) and the transforamtion into sporocyst may be separated into three phases. (1) Less than 1 min after attachment to the snail the ciliated cells of the anterior tier are shed and swim away. (2) The cilia of the remaining cells beat violently and after about 5 min most cilia are broken off near the cell surface. The miracidium remains for about 15 min embedded as far as the intracellular ridge receptors (lateral papillae and sheathed ciliated nerve endings). During this period extensive contraction and relaxation of the body are performed. (3) The final penetration of the snail epithelium takes about 15 min. Simultaneously with the penetration into the snail tissue the "bald" cells (epithelial cells with cilium stubs only) of the four posterior tiers loosen, florm globules and fall off. The surface below the cells is smooth and in cytoplasmic continuity with the intercellular ridge and the apical papilla, and this syncytium forms the later tegument of the sporocyst. After a few days the tegument of the sporocyst is provided with microvillus-like projections and the apical papilla and sensory structures are lost.     

Regeneration of nasopharyngeal epithelium in Macaca fascicularis.

Regeneration of the nasopharyngeal epithelium in Macaca fascicularis occurs as a result of migration of epithelial cells from the margins of the lesions as well as from the neighbouring glandular ducts and epithelial crypts. The study further reveals that the basal cells are the progenitors of both goblet and ciliated cells. The regenerating epithelium at first consists of mucus-containing cells which are finally converted into normal globlet and ciliated cells. The formation of centrioles and concurrent reduction in the amount of 'mucus' droplets, and rearrangement of centrioles towards the luminal surface of the cells along with simultaneous development of cilia in some of these mucus-containing cells are stages in the differentiation of ciliated cells. However, some cells which do not possess secretory droplets may also develop into ciliated cells directly.     

Temporal and spatial distribution of ciliogenesis in the tracheobronchial airways of mice

Little is known about ciliogenesis as it proceeds through the entire airway tree, from the trachea to the terminal bronchioles, especially during the postnatal period. The purpose of this study was to define the spatial and temporal (prenatal and postnatal) pattern of normal cilia development in the mouse. Three airway generations representing the entire airway tree were examined: trachea, lobar bronchi, and terminal bronchiole. Ciliated cells in lung lobe whole mounts were labeled with a fluorescent dye for confocal microscopy, and ciliated cell surface density was measured for each airway generation and age. The same samples were examined by scanning electron microscopy to verify the appearance of ciliated cells among the differentiating epithelium of the airways. Ciliated cells were first detected in the trachea and lobar bronchi at 16 days gestational age (DGA) and in the terminal bronchioles at 18 DGA. Ciliated cell surface density increased with prenatal and postnatal age at all airway levels. However, the ciliated cell surface density of the trachea and lobar bronchi was always greater compared with the terminal bronchiole. In conclusion, the study revealed that in developing tracheobronchial airways of the mouse: 1) Ciliogenesis differs temporally and spatially by airway generation; 2) Ciliated cell surface density increases with age in all airway generations, but density decreases in a proximal to distal direction; and 3) A significant portion of ciliogenesis continues after birth. This study provides a healthy basis for investigations of neonatal pulmonary disease or pollutant toxicity affecting cilia and its functions.     

Morphology and quantitation of ciliated outgrowths from cultured rabbit tracheal explants

Ciliated outgrowths from cultured rabbit tracheal epithelium have been characterized with scanning and transmission electron microscopy and the ciliary frequencies measured. Outgrowth surface cells change in morphology from columnar to cuboidal to squamous shapes in their progression away from the explant. The ciliated cells retain the organization of their cilia in a cluster usually centrally on the apical cell surface. Closest to the explant the nonciliated surface of ciliated cells develops extensive microvilli. Ciliary frequencies are comparable to those observed in fresh tracheal epithelium with means of 50 cells per explant ranging from 11 to 23 beats per second. For most cultures examined no correlation exists between ciliary frequency and cell distance from the explant. The goblet cells loose their ability to synthesize the characteristic mucus granules and can only be identified by the absence of cilia. Surface cells are supported by an underlying layer of discontinuous cells and connective tissue fibers. The characteristics of an outgrowth suggest that development occurs through migration of differentiated cells from the explant rather than differentiation of cell types from migrating basal cells.     

The ultrastructure of the rat esophageal epithelium during ontogenesis]

The development of the epithelium of the rat esophagus was examined continuously from the 13th day post-conception until one day post-partum. Besides the single-results at different phases of development the knowledge, that the esophageal ontogeny of different mammalians may be considerably different, is of special importance. To this matter of fact was not paid attention in present literature, but the authors accentuate common things. The significant results during development are the following: 1. The completely undifferentiated epithelium of the 13th day at the same time develops basement-membrane and basic membrane of the cytoplasm. The organelles are under construction. Centriols in cells near to the lumen are seen in connection to the single-cilia, which occur till the 17th day of ontogeny. These essentially differ from cilia of the ciliated epithelium. 2. The cylindrical epithelium constitutes until the 16th day. Afterwards the first synthetic productivity like organisation of filaments are observed. By that superficial cells loose their capacity to divide. 3. On the 17th day intercellular spaces between neighbouring cells at the lumen abruptly rip up. In loco cylindrical cells change to squamous cells. There are no essential differences in time between cranial and caudal parts of the esophagus which proofs an entodermal genesis of the epithelium. 4. Changes in the ultrastructure at about 19 days p.c. cause the epithelium's keratinization. 5. 21 days p.c. few cilia-bearing cells scattered between the cells in keratinization are to be seen. 6. Before birth superficial cells become separated and are shed from the surface completely post-partum.     

A SEM study of the olfactory lamellae of the catfish Heteropneustes fossilis (Bl.)

The olfactory lamellae of the catfish H. fossilis (Bl.) was studied in the scanning electron microscope. The olfactory lamellae are composed of sensory and non-sensory epithelium. The sensory epithelium contains large numbers of ciliated receptor cells, whereas the non-sensory raphe epithelium is covered with a dense mat of non-sensory cilia. It is not known whether the olfactory cilia possess receptor sites.     

Ultrastructural studies on the epithelia of the olfactory organ of cyprinodonts (teleostei,cyprinodontoidea)

Summary The epithelia of the olfactory organ of two cyprinodontoid fish species were studied both by transmission and scanning electron microscopy. The relatively flat floor of the organ is covered by sensory and nonsensory epithelia. The latter is distributed in the form of bands or ridges separating distinct areas of sensory epithelium. Differences between the olfactory organs of the two species investigated related only to the topography and quantitative distribution of the epithelia. Their ultrastructural features are very similar. The nonsensory stratified squamous epithelium contains numerous goblet cells and surface cells provided with microridges. A hypothetical function of the microridges is discussed. The sensory epithelium consists mainly of basal, supporting, and two types of sensory cells, i.e., ciliated and microvillous receptor cells. The cilia exhibit a predominant 9+0 microtubule pattern. Both epithelia are covered by a mucus layer in which all surface structures seem to be embedded. The possible nature, origin, and movement mechanisms of the mucus are discussed.This work was supported by the Deutsche ForschungsgemeinschaftDedicated to Prof. Dr. med. W. Bargmann on the occasion of his 70th birthday     

Paddle cilia (discocilia) in chemosensitive structures of the gastropod mollusk Pleurobranchaea californica

Summary Scanning electron microscopy of various regions of the body of the marine gastropod Pleurobranchaea californica (McFarland) has revealed a characteristic cell type that bears cilia with dilated discoid-shaped tips. The tips of the cilia consist of an expansion of the ciliary membrane around a looped distal extension of the axoneme. These kinocilia have been observed in numerous other marine invertebrates and are generally referred to as paddle cilia (Tamarin et al. 1974) or discocilia (Heimler 1978). Although many functions have been proposed for paddle cilia, little empirical evidence supports any of the proposals. In Pleurobranchaea we have found that the distribution of this ciliated cell type corresponds exactly to areas of the body known from behavioral studies (Lee et al. 1974; Davis and Matera 1981) to mediate chemoreception. Transmission electron microscopy of the epithelium lining the rhinophores and tentacles of Pleurobranchaea revealed details of the ultrastructure of these ciliated cells and showed that they are primary receptors. These ciliated receptors lie in a yellow-brown pseudostratified columnar epithelium that superficially resembles the olfactory mucosa of vertebrates.     

Tissue expression patterns identify mouse cilia genes.

In mammals, cilia are critical for development, sensation, cell signaling, sperm motility, and fluid movement. Defects in cilia are causes of several congenital syndromes, providing additional reasons to identify cilia-related genes. We hypothesized that mRNAs selectively abundant in tissues rich in highly ciliated cells encode cilia proteins. Selective abundance in olfactory epithelium, testes, vomeronasal organ, trachea, and lung proved to be an expression pattern uniquely effective in identifying documented cilia-related genes. Known and suspected cilia-related genes were statistically overrepresented among the 99 genes identified, but the majority encoded proteins of unknown function, thereby predicting new cilia-related proteins. Evidence of expression in a highly ciliated cell, the olfactory sensory neuron, exists for 73 of the genes. In situ hybridization for 17 mRNAs confirmed expression of all 17 in olfactory sensory neurons. Most were also detected in vomeronasal sensory neurons and in neighboring tissues rich in ciliated cells such as respiratory epithelium. Immunoreactivity for one of the proteins identified, Spa17, colocalized with acetylated tubulin in the cilia layer of the olfactory epithelium. In contrast, the ciliary rootlet protein, Crocc, was located in discrete structures whose position was consistent with the dendritic knobs of the olfactory sensory neurons. A compilation of >2,000 mouse genes predicted to encode cilia-related proteins revealed a strong correlation (R = 0.99) between the number of studies predicting a gene's involvement in cilia and documented evidence of such involvement, a fact that simplifies the selection of genes for further study of the physiology of cilia.